1. Field of the Invention
The present invention relates to a vehicle position detection system and, more specifically, to a detection system employing radio waves.
2. Description of the Related Art
Methods for detecting a relative position of a vehicle to a road, which is for automatic driving of a vehicle, are known.
For example, in Japanese Utility Model Laid-Open Publication No. Hei1-106910, a method for detecting a vehicle attitude using paving light reflecting tape installed on a road and a pair of photo sensors installed on a vehicle with a width less than that of the light reflecting tape has been disclosed. Another method of detecting the position of a vehicle relative to white lines by recording a road surface using an in-vehicle camera and extracting the white lines in a screen is also known.
However, if a light reflecting tape is used, sufficient reflection may not be obtained in some cases due to dirt on the tape as, unlike in indoor test situations, actual road surfaces are always affected by rain, snow, or the like. Especially, in the case of rain, puddles of water reflect light very well, which is problematic for high accuracy vehicle position detection. Even when in-vehicle cameras tend to be affected by the weather. Under rainy conditions, there is insufficient contrast between the white lines and other areas of the road surface, and the white lines can not be extracted with high accuracy.